Changes

# After every large storm event (e.g., 15 mm rainfall depth or greater) to ensure ESCs and pretreatment or flow diversion devices are functioning and adequately maintained.  View the table below, which describes critical points during the construction sequence when inspections should be performed prior to proceeding further. You can also download and print the table [https://wikidev.sustainabletechnologies.ca/images/a/a6/LID-IM-Guide-7.5-Underground-Infiltration-Systems.pdf '''here''']<br>

# After every large storm event (e.g., 15 mm rainfall depth or greater) to ensure ESCs and pretreatment or flow diversion devices are functioning and adequately maintained.  View the table below, which describes critical points during the construction sequence when inspections should be performed prior to proceeding further. You can also download and print the table [https://wikidev.sustainabletechnologies.ca/images/a/a6/LID-IM-Guide-7.5-Underground-Infiltration-Systems.pdf '''here''']<br>

</br>

</br>

[[File:Catchbasin isnert underground.PNG|thumb|400px|A [[pretreatment]] device (catchbasin insert) upstream of an underground infiltration system inlet in need of cleaning out. These devices are designed to limit the amount of trash, debris, sediment, oil and grease entering the infiltration system, which helps to prevent clogging and maintain its drainage performance  (Source: TRCA, 2018<ref name="example1" />).]]  

[[File:Catchbasin isnert underground.PNG|thumb|400px|A [[pretreatment]] device (hydrodynamic (i.e., oil and grit) separator) upstream of an underground infiltration system inlet in need of cleaning out. These devices are designed to limit the amount of trash, debris, sediment, oil and grease entering the infiltration system, which helps to prevent clogging and maintain its drainage performance  (Source: TRCA, 2018<ref name="example1" />).]]  

{| class="wikitable" style="width: 800px;"

{| class="wikitable" style="width: 800px;"

==Routine Maintenance - Key Components and I&M Tasks==

==Routine Maintenance - Key Components and I&M Tasks==

Regular inspections (twice annually, at a minimum) done as part of routine maintenance tasks over the operating phase of the BMP life cycle to determine if maintenance task frequencies are adequate and determine when rehabilitation or further investigations into BMP function are warranted.

Regular inspections (twice annually, at a minimum) done as part of routine maintenance tasks over the operating phase of the BMP life cycle to determine if maintenance task frequencies are adequate and determine when rehabilitation or further investigations into BMP function are warranted.

Table below describes routine maintenance tasks for underground infiltration systems ([[infiltration chambers]], [[infiltration trenches]], [[bioswales]], etc.) organized by BMP component, along with recommended minimum frequencies. It also suggests higher frequencies for certain tasks that may be warranted for BMPs located in highly visible locations or those receiving flow from high traffic (vehicle or pedestrian) areas. Tasks involving removal of trash, debris and sediment and weeding/trimming of vegetation for BMPs in such contexts may need to be done more frequently (i.e., higher standards may be warranted).  

Table below describes routine maintenance tasks for underground infiltration systems ([[infiltration chambers]], [[infiltration trenches]], [[bioswales]], etc.) organized by BMP component, along with recommended minimum frequencies. It also suggests higher frequencies for certain tasks that may be warranted for BMPs located in highly visible locations or those receiving flow from high traffic (vehicle or pedestrian) areas. Tasks involving removal of trash, debris and sediment and weeding/trimming of vegetation for BMPs in such contexts may need to be done more frequently (i.e., higher standards may be warranted).  

|'''[[Pretreatment]]'''

|'''[[Pretreatment]]'''

|

|

Devices or features that retain trash, debris and sediment, oil and grease; help to prevent obstructions and [[clogging]] of the infiltration area. Examples are eavestrough screens, [[Pretreatment|catch basin]] inserts (screens, baffles, fitlers) and sumps, [[oil and grit separators]], [[inlets|geotextile-lined inlets]], filters, isolator rows, and water quality [[forebay]] units.  

Devices or features that retain trash, debris and sediment, oil and grease; help to prevent obstructions and [[clogging]] of the infiltration area. Examples are eavestrough screens, [[Pretreatment|catch basin]] inserts (screens, baffles, filters) and sumps, [[oil and grit separators]], [[inlets|geotextile-lined inlets]], filters, isolator rows, and water quality [[forebay]] units.  

|

|

*Remove trash, debris and sediment annually to biannually or when the device sump is half full;

*Remove trash, debris and sediment annually to biannually or when the device sump is half full;

*Measure sediment depth or volume during each cleaning, or annually to estimate accumulation rate and optimize frequency of maintenance.

*Measure sediment depth or volume during each cleaning, or annually to estimate accumulation rate and optimize frequency of maintenance.

|[[File:Pretreat Pass p.p.JPG|280px|thumb|center|Although permeable pavers are generally considered [[pretreatment]] for other BMPs in a [[Low impact development treatment train tool|treatment train]] system, using eavestrough screens can act as pretreatment as they don't add to sediment build up and accumulation on the paver surface. (Photo Source: Guertin, 2010)<ref>Guertin, M. 2010. Simple Screen Gutter Guards Better Than Pro-Installed Systems (and way cheaper). Fine Homebuilding - The Daily Fix. Accessed July 17 2022. https://www.finehomebuilding.com/2010/08/17/simple-screen-gutter-guards-better-than-pro-installed-systems-and-way-cheaper</ref>]]  

|[[File:Pretreatment inlet pass underground.PNG|280px|thumb|center|[[Geotextile]]-lined stone inlet is free of sediment, trash and debris. Stones to slow down and spread out inflowing water remain in place.]]

|[[File:Pretreat Fail p.p.JPG|300px|thumb|center|Build up of leads, sediment and leaf detritus in an eavestrough downspout disconnection leading to a permeable pavement surface. If not cleaned regularly this can lead to clogged pores between the pavers reducing the infiltration rate where the downspout deposits water onto the feature. (Photo Source: My Gutter Pro, 2021)<ref>My Gutter Pro. 2021. Clogged Downspout : Causes and Solutions. 10 April 2021. Accessed July 19 2022. https://mygutterpro.com/downspout-clog/</ref>]]  

|[[File:Pretreatment inlet Fail underground.PNG|300px|thumb|center|Accumulated sediment, trash and debris in the hydrodynamic (i.e., oil and grit) separator is occupying greater than 50% of its storage capacity. (Photo Source: SWC Canada, 2020)<ref>Storm Water Compliance (SWC) Canada Inc. 2020. OIL GRIT SEPARATORS/WATER QUALITY STRUCTURES. Accessed 02 August 2022. https://www.swccanada.com/system-types/oil-grit-separators</ref>]]  

|-

|-

|'''[[Inlets]]'''

|'''[[Inlets]]'''

*Remove trash, sediment and debris biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter);

*Remove trash, sediment and debris biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter);

*Make note of sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance.

*Make note of sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance.

|[[File:Inlet Pass p.p.JPG|285px|thumb|center|Impermeable pavement edges along the edge of the pervious concrete and impermeable asphalt graded so excess sheet flow is infiltrated down through the pores of the infiltration BMP. (Photo Source: Fairfax County, 2014)<ref>Fairfax County. 2014. Protecting our Environment, one Stormwater Practice at a Time - Permeable Pavements. April 2014. Accessed: July 20 2022. https://www.fairfaxcounty.gov/publicworks/sites/publicworks/files/assets/documents/pdf/factsheets/permeable-pavement.pdf</ref>]]  

|[[File:Inlets pass underground.PNG|285px|thumb|center|There are no obstructions at the inlet and stormwater can freely flow into the BMP.]]  

|[[File:Curb inlet grade.jpg|300px|thumb|center|Accumulated sediment, poor grading and vegetation is preventing stormwater from entering the [[swale]]. Sediment on the curb cut surface behind of the inlet indicates ponding is also occurring and is depositing water towards the permeable paver surface.]]  

|[[File:Inlets fail underground.PNG|300px|thumb|center|Sediment has accumulated in the inlet pipe to the infiltration trench and is fully obstructing flow of stormwater into the BMP.]]  

|-

|-

|'''[[Overflow|Overflow Outlet]]'''

|'''[[Overflow|Overflow Outlet]]'''

*Keep free of obstructions;

*Keep free of obstructions;

*Remove trash, sediment, debris, oil and grease biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter).

*Remove trash, sediment, debris, oil and grease biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter).

|[[File:Overflow Pass p.p.JPG|320px|thumb|center|The overflow outlet is free of damage and obstruction and functions as designed to safely convey excess water from the BMP.]]  

|[[File:Outlet & overflow pass underground.PNG|320px|thumb|center|The overflow outlet weir wall and storm sewer pipe in the control manhole of this infiltration chamber system is free of damage and obstruction and functions as designed to safely convey excess water from the BMP.]]  

|[[File:Overflow Fail p.p.JPG|280px|thumb|center|The overflow outlet is obstructed with sediment which impairs its function to convey excess water from the BMP.]]  

|[[File:Overflow Fail p.p.JPG|280px|thumb|center|Sediment and debris has accumulated in the overflow outlet pipe which impairs its function to convey excess water from the BMP.]]  

|-

|-

|'''[[Underdrain|Sub-drain]]'''

|'''[[Underdrain|Sub-drain]]'''

|

|

*Keep perforated pipes and flow restrictors free of obstructions;

*Keep perforated pipes and flow restrictors free of obstructions;

*Inspect flow restrictor and flush with a garden hose or pressure washer regularly (biannually to quarterly);

*Inspect flow restrictor and flush with a garden hose or pressure washer regularly (biannually to quarterly).

|[[File:Underdrain Pass p.p.JPG|310px|thumb|center|The solid section of the sub-drain pipe is not obstructed by sediment, debris or roots and shows no signs of damage.]]  

|[[File:Underdrain pass underground.PNG|310px|thumb|center|The sub-drain outlet pipe from the infiltration chamber system is not obstructed by sediment, debris or roots and shows no signs of damage.]]  

|[[File:Underdrain Fail p.p.JPG|300px|thumb|center|A section of the sub-drain pipe has been crushed which substantially reduces its conveyance capacity]]  

|[[File:Underdrain fail underground.PNG|300px|thumb|center|A perforated pipe in an exfiltration storm sewer system is clogged by sediment and debris which inhibits its drainage function.]]  

|-

|-

|'''[[Monitoring well]]'''

|'''[[Monitoring well]]'''

|

|

*[[Wells|Standpipes]] should be securely capped on both ends and protected from damage by vehicular traffic or foot traffic by a lockable casing.

*[[Wells|Standpipes]] should be securely capped on both ends and protected from damage by vehicular traffic or foot traffic by a lockable casing.

|[[File:Monitor Pass p.p.JPG|340px|thumb|center|The well is undamaged and accessible and the cap is in place and secured to prevent unauthorized access]]  

|[[File:Monitoring well pass underground.PNG|340px|thumb|center|The well is undamaged and accessible and the cap is in place and secured to prevent unauthorized access]]  

|[[File:Monitor Fail p.p.JPG|300px|thumb|center|The well cap is missing and the casing is clogged by sediment, preventing access for monitoring and allowing sediment to flow into the sub-drain system.]]  

|[[File:Monitoring well fail underground.PNG|300px|thumb|center|The well was buried during landscaping and found covered only by filter cloth (i.e. cap missing).]]

 

*For BMPs with [[underdrains|sub-drains/underdrains]] and flow restrictors, [[Pretreatment|pretreatment devices]] that prevent floating trash and debris from entering the practice should be used to prevent obstruction of the sub-drain pipe/flow restrictor.

*Provide a means of draining [[infiltration chambers]] by gravity (e.g., pipe and valve through the control structure weir wall) to make [[inspection and maintenance]] work that requires drainage of the BMP (e.g., filter bed and control structure inspection and sediment removal, repairs to control structure) easier to perform.

*To remove accumulated sediment from [[underdrain]] pipes and chamber system units, a hydrovac truck equipped with a JetVac nozzle should be employed that uses pressured jets of water to propel itself through the structure while scouring and directing suspending sediments to a collection point. As the nozzle is retrieved, the sediment is flushed into the manhole or catchbasin sump for removal by vacuuming. Selecting an appropriate JetVac nozzle will depend on the structure being cleaned. For chamber system units, fixed nozzles designed for culverts or large diameter pipe cleaning with rear-facing jets are preferable (consult product manufacturer for further guidance).

 

 

Table below provides guidance on rehabilitation and repair work specific to underground infiltration systems organized according to BMP component.<br>

 

[[File:Underdrain clogded underground.PNG|thumb|340px|The manhole sump is becoming filled with sediment, trash and excess and debris, which is beginning to impair flow of stormwater into the [[perforated pipe]] of the [[exfiltration trench|exfiltration storm sewer system.]]]]

 

*Schedule hydro-vac truck or drain-snaking service to remove the obstruction.

*Replace missing or damaged caps.

|'''[[Forebays|Isolator Row or Water Quality Forebay Unit]]'''

|-

|-

|}

|}